Re: [PATCH] Optimization calculation expression of Macro

[WILLIAM NEW]

Just to remove the common factor: "sizeof (grub_addr_t)"  from the
numerator and denominator of the fractional expression of next var.
Let me explant it:
Shortly:
H: struct grub_module_header ;
B: grub_uint32_t ;
A: grub_addr_t;

Thus, original expression can be expressed as:
var = (H *)((B*)var) + ( offset_exp ))
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++
             (((H*)var)->size + sizeof(A) - 1)    sizeof(A)  |
offset_exp = --------------------------------- * ----------- |
                      sizeof(A)                   sizeof(B)  |
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Remove the common factor "sizeof(A)" of fractional offset_exp, we got
the result.
offset_exp_new = ((H*)->size + sizeof(A) - 1) / sizeof(B)
                   = ((struct grub_module_header *) var)->size +
sizeof (grub_addr_t) -1) / sizeof (grub_uint32_t)

so:
var =(H *)(((B*)var) + ( (((H*)var)->size + sizeof(A) - 1) / sizeof(B) ))


Still, the new offset express is meaningfull:
numerator: ((struct grub_module_header *) var)->size + sizeof (grub_addr_t) -1)
          it present the offset value united by byte.
denominator: sizeof (grub_uint32_t)
it's means "struct grub_module_header" alligned by sizeof(grub_uint32_t)

Please feel free to contact me if you need any further information.